1. Field of the invention:
This invention relates to a method and an apparatus for packing a compound which is in a solid or a semi-fluid state at a normal temperature (hereinafter referred to as a semisolid compound), such as asphalt, tar and pitch, in bags made of thermoplastic high polymer material film.
2. Prior art:
Asphalt, for example, is usually transported as it is packed in drums but each asphalt drum weighs some 200 kgs. and it is inconvenient to handle such weighty drums. Furthermore, it requires labor to handle empty drums after the contents are used. In this connection, a method of packing such materials in paper bags or the like has been suggested (for example, Japanese Patent Application Publication Gazette No. 41-22177), but it is troublesome to unpack each paper bag when the contents are used.
The inventors previously suggested a method of packing asphalt in a polyethylene resin bag (about 20 kg. in each bag) having a softening point lower than asphalt in a fluid state while cooling the bag, so that such bags of comparatively light weight can be transported easily and the bags themselves can be melted directly into asphalt, when asphalt is used, with resultant weight increasing and reinforcing effect on asphalt (Japanese Patent Application No. 58-1004).
The present invention is an improvement on the above method and has for its object to provide a novel method of packing and an apparatus therefor, by which a series of packing operations can be carried out effectively and compactly.